The E.164 Number Mapping (ENUM) system has been developed by the Internet Engineering Task Force (IETF) for facilitating the interconnection of communications networks that rely on telephone numbers with the communications networks that utilize the Domain Name System (DNS). In particular, the ENUM system assists with the convergence of the Public Switched Telephone Network (PSTN) and Internet protocol (IP) networks. The ENUM system can map a particular number referred to as an E.164 number to one or more Uniform Resource Identifiers (URIs) in the DNS. URIs are strings of characters that identify resources such as documents, images, files, databases, e-mail addresses, websites or other resources or services in a common structured format. A URI can include a SIP URI, an instant messaging (IM) identifier, an e-mail address identifier, an Internet chat session identifier, and an IP address. The ENUM system provides a solution to the problem of finding services on the Internet using only a telephone number.
In one example, the use of the ENUM system may be initiated when a user of a conventional telephone dials a called party number (referred to herein as an E.164 telephone number) for reaching another telephone. An ISDN User Part (ISUP) Initial Address Message (IAM) containing the called party number is routed to the Public Switched Telephone Network (PSTN). The PSTN can then communicate an ISUP IAM message containing the E.164 telephone number to a gateway. The gateway can convert the E.164 telephone number into ENUM message format for transmission in an ENUM query. The E.164 telephone number is converted to ENUM message format by reversing the digit order of the dialed E.164 telephone number and appending the highest level domain e164.arpa to the end. For example, if the original E.164 number is 123-456-7890, the ENUM query is converted 0.9.8.7.6.5.4.3.2.1.e164.arpa (also referred to herein as an E.164 telephone number). Next, the ENUM query is communicated to an ENUM server. The ENUM server uses the ENUM query to retrieve one or more naming authority pointer (NAPTR) records associated with the E.164 number. Each of the NAPTR records may identify at least one URI corresponding to the user with the E.164 telephone number. The URI is then communicated to the gateway in an ENUM response for establishing communication between the telephones.
In an international ENUM networking environment, an ENUM server may receive ENUM queries from gateways associated with different country codes. For example, the ENUM server may receive ENUM queries from gateways national networks located in France and Italy. These different national networks have different country codes. This situation can be problematic for an ENUM server when an ENUM query is received that includes an E.164 telephone number without a country code prefix and the same E.164 telephone number is valid in multiple countries. In this case, the ENUM server would not be able to identify the gateway to which to respond with an ENUM response. Thus, it would be advantageous to be able to determine a country code prefix based on information in an ENUM query that includes an E.164 telephone number without a country code prefix.
Accordingly, based on the foregoing, there exists a need for methods, systems, and computer program products for determining a country code prefix based on information in an ENUM query that includes an E.164 telephone number without a country code prefix.